Jiafei Zhang and David W. Agar

Transcription

1 Shell s research project: Development of novel amine absorbents for CO 2 capture Efficient Carbon Capture for Coal Power Plants Session M1: Chemical Absorption Materials and David W. Agar Technische Universität Dortmund, Germany Frankfurt a.m

2 Outline Motivation Novel concepts Novel solvents Challenges and improvement Summary 1

3 Outline Motivation Novel concepts Global warming Shortcomings of conventional solvents Advantages of novel biphasic solvents Novel solvents Challenges and improvement Summary 2

4 Motivation CO 2 emission global warming CO 2 Capture & Storage (CCS) Amine-based absorption process is the dominant commercial technology for CO 2 capture Challenges? New generation absorbents Technical shortcomings of conventional solvents: e.g. monoethanolamine (MEA) High energy consumption High quality of heat: C Significant amine loss by degradation Major superiorities of novel biphasic solvents: Regeneration temperature 80 C Use of waste heat for desorption Good chemical stability High net CO 2 loading capacity Wet CO 2 corrosion CO 2 + H 2 O HCO H + Anodic Fe Fe 2+ +2e - Catodic 2H + + 2e - 2H 0 Wet CO 2 corrosion CO 2 + H 2 O HCO H + Amine corrosion + Fe + 2RNH 3 Fe H 0 + 2RNH 2 3

5 Outline Motivation Novel concepts Novel solvents Lipophilic amine Phase change TBS absorbent b Other CO 2 capture process with LLPS Challenges and amelioration Liquid-liquid phase separation (LLPS): Summary 4

6 Concepts I Novel amines Alkanolamine vs lipophilic amine Hydrophobic Hydrophilic (H)R N R(H) (H)R N R(H) NH 2 R OH R Examples of lipophilic amine Hexylamine (I) HA N Dipropylamine (II) DPA N,N-Dimethylcyclohexylamine (III) DMCA N H 5

7 Concepts II Phase change Thermomorphic phase transition Low temperature single phase High temperature dual phases Lower critical solution temperature (LCST) Hexylamine (I) A1 DPA (II) DMCA (III) Frozen Temperature [ 癈 ] Two phases 0 Single phase -20 Expected 0,0 0,2 0,4 0,6 0,8 1,0 Mass fraction of lipophilic amine in aqueous solution [g/g] 6

8 Concepts III Novel absorbent: b thermomorphic hi biphasic i solvent (TBS) Absorption: Regeneration: single phase single phase two phases Lean solvent cooling to C: homogeneous Rich solvent heating to C: biphasic (a) Homogeneous absorption (b) Heterogeneous desorption CO 2 Heating Organic phase R R 2 R 3 N + CO 2 + H 2 O R 1 R 2 R 3 NH HCO 3 3 R R 2 R 3 N + CO 2 + H 2 O R 1 R 2 R 3 NH HCO 3 3 Aqueous phase Cooling CO 2 Process Flow Sheet 7

9 Concepts IV Other CO 2 capture process with LLPS Self-Concentration CO 2 DMX TM process with Capture Process demixing i solvents Univ. of Kentucky IFP Energies Nouvelles Heat Ref.: Hu, 2010 Annual NETL CO 2 Capture Technol. R&D Meeting. Lemaire, et al., 12th Intl. Network for CO 2 Capture,

10 Outline Motivation Novel concepts Novel solvents Ideal solvent Absorption Desorption Chemical stability Amine selection Challenges and improvement Summary DMX-1, r) P CO2 (mbar 癈 A1+DsBA, 30 癈 A1+DsBA, 80 癈 MEA 30wt%, 40 癈 MEA 30wt%, 120 癈 Loading (mol -CO2 /kg -sol. ) 9

11 The ideal chemical solvent for PCC (Davidson, 2007) Novel solvents High reactivity (kinetics) reduces height requirements for the absorber and/or solvent circulation flow rates High absorption capacity directly influences solvent circulation flow rate requirements Low regeneration costs reduced energy consumption High thermal stability and low solvent degradation reduced solvent waste due to thermal and chemical degradation Low solvent costs should be easy and cheap to produce Low environmental impact Technical feasibility Reactivity Absorption capacity Energy consumption Stability 10

12 Absorption Reactivity Rapid reaction rate Comparable to MEA (when α<0.5) Loading of CO 2 [m mol CO 2 / mol amine] Novel solvents I 1,0 TBS 0,8 0,6 MEA 0,4 MDEA+MEA 0,2 0, Time [min] Loading capacity (net) mo ol -CO2 /kg -sol Alkanolamine C 2 w/ steam stripping 1,5 TBS absorbent C 1 w/o steam stripping 0,5 CO 2 absorbed in TBS: 3.4 mol/kg 0 Higher than MEA and AMP 3,5 3 2,5 Reactivity i Absorption capacity Energy consumption VLE Stability 11

13 Novel solvents II Desorption Liquid-liquid phase separation Low regeneration temperature ca. 80 C Low value heat Before regeneration During regeneration After regeneration High regenerability > 80% at 80 C for most TBS > 98% at 80 C for optimised TBS Estimated energy consumption MEA: 4.0 GJ/t -CO2 TBS: 2.5 GJ/t -CO2 Ref.: Geuzebroek, et al., TCCS-5, 2009 Reactivity i Absorption capacity Energy consumption VLE Stability 12

14 Novel solvents III Vapour-liquid id equilibrium i Higher CO 2 loading Lower residual loading Better than benchmarks P CO2 (mba ar) DMX-1, 40 癈 A1+DsBA, 30 癈 A1+DsBA, 80 癈 MEA 30wt%, 40 癈 MEA 30wt%, 120 癈 Loading (mol -CO2 /kg -sol. ) Chemical stability Low temperature (80 C) for desorption less thermal degradation Percent [% ] Basicity reduction by oxidative degradation Reactivity it reduction by CO 2 induced d degradationd Reactivity reduction by oxidative degradation Reactivity reduction by catalyzed oxidative degradation B1 A1 MEA Low oxidability less 20 oxidative degradation 0 B1 A1 MEA MDEA Solvent Reactivity i Absorption capacity Energy consumption VLE Stability 13

15 Screening tests searching new amines > 60 lipophilic amines (alkylamines) 10 comparable to MEA or MDEA Criteria High loading capacity: > 0.6 mol/mol (15% CO 2 ) Fast absorption rate: comparable to MEA Good regenerability: better than MDEA Low degradability: comparable to AMP & MDEA Moderate heat of reaction: lower than MEA Novel solvents IV HN DPA N A A: partially soluble in water, rapid absorption rate as absorption activator e.g. HX, DPA, A1 DMCA B: less miscible with water, high regenerability as regeneration promoter e.g. DMCA, EPD, B1 Recommended absorbent: blended solvent A+B Blending A+B exploits the strengths of both components N EPD 14

16 Outline Motivation Novel concepts Novel solvent Challenges and improvement Summary Vaporisation loss Phase transition Regeneration techniques Process development 15

17 Challenges and improvement I Amine vaporisation loss Countermeasures High volatility Significant ifi volatile loss Tf for feed d(t (top) at t30 C Amine Temp. Loss A1 DMCA DMCA+A1 (3:1) C %/day 30 < MEA AMP Reduced vaporisation Hydrophobic solvent scrubbing e.g. Diphyl Recovery >80% Water wash when using A1 as primary solvent Reduced amine loss Comparable to MEA or AMP 16

18 Challenges and improvement II Phase transition Countermeasures Temperature ( 癈 ) Lower critical solution Concentrating temperature (LCST): Negative on vaporisation loss most lipo. Amines < 20 C Limited at 4M Problem: biphasic solvent in absorber Using more A1 Negative on regeneration 50 LCST 20 C PTT of DMCA+A1 with 9wt% AMP CST of DMCA+A1 with 9wt% AMP PTT of DMCA+A1 CST of DMCA+A1 Two phases emulsion emulsion Single phase PTT: phase transition temperature CST: critical solution temperature 3M(2:1) 3M(1:1) 4M(2:1) 4M(1:1) Concentration (mol/l) Partial deep regeneration Residual loading 0.1 Increasing LCST to 30 C Adding solubiliser <10wt% Increasing LCST to 40 C 17

19 Regeneration techniques Challenges and improvement III Challenges Regeneration intensification Low temperature 80 C Without steam Extractive regeneration + Regeneration promoter How to intensify the regeneration? Agitation Nucleation Nucleation + Agitation 18

20 Challenges and improvement III Extractive regeneration with regeneration promoter (B) Solution: B1+A1+water (loaded with CO 2 ) After absorption: homogeneous loaded solution Gas Phase Single Liquid Phase 19

21 Challenges and improvement III Extractive regeneration with regeneration promoter (B) Solution: B1+A1+water (+CO 2 ) After absorption: homogeneous loaded solution Start of desorption CO 2 is first liberated from B1 Gas Phase B1 CO 2 A1+CO 2 H 2 O Single Liquid Phase (Heat) 20

22 Challenges and improvement III Extractive regeneration with regeneration promoter (B) Solution: B1+A1+water (+CO 2 ) After absorption: homogeneous loaded solution Start of desorption: CO 2 is first liberated from B1 B1 is insoluble in water, regenerated B1 accumulates Separate supernatant organic phase is formed Gas Phase B1 CO 2 A1+CO 2 H 2 O Aq. Phase (Heat) B1 21

23 Challenges and improvement III Extractive regeneration with regeneration promoter (B) Solution: B1+A1+water (+CO 2 ) After absorption: homogeneous loaded solution Start of desorption: CO 2 is first liberated from B1 B1 is insoluble in water, regenerated B1 accumulates Gas Phase Separate supernatant organic phase is CO 2 A1 formed A1 preferentially dissolves in the organic rather than the aqueous phase H 2 O B1 adopts the role of a solvent, extracting A1 from the aqueous phase (Heat) B1 Org. Phase Aq. Phase 22

24 Extractive regeneration with regeneration promoter (B) LLSP temperature Activator (A): 90 C Promoter (B): C Acti. Prom. Challenges and improvement III A1 DPA HA EPD DMCA B LLSP temperature ( C) 100 Regenerability at 80 C 80 Activator (A): 45-50% Promoter (B): 90-95% Acti.+Prom. (A:B=3:1): 85-90% Regenerability (%) Activator Promoter Acti.+Prom. 23

25 Nucleation & Agitation Challenges and improvement IV 2,0 Solution: A1+B1, 2+1M at 75 癈 1,6 Agitation Nucleation Stirring Desorber CO 2 (mol/l) 1,2 0,8 750 rpm 0,4 500 rpm 250 rpm N 2 stripping 0, Time (min) Desorber CO 2 (mol/l) 2,0 1,6 1,2 0,8 Solution: A1+B1, 2+1M at 75 癈 1/40 wt. 0,4 1/60 wt. 1/80 wt. N 2 stripping 0, Time (min) Porous particles for CO 2 bubble formation release rate [g/l/hr] CO DMCA+A1 DMCA+DPA Agitation none 100 rpm 250 rpm 500 rpm 750 rpm 1000 rpm Stripping Method 24

26 Challenges and improvement V Process development Regeneration without steam stripping Flow sheeting diagram 25

27 Challenges and amelioration V Bench-scale experimentation in packed absorption columns Absorber Regenerator Bottom of absorber b At TU Dortmund At Shell G.S. 26

28 Summary Novel absorbent: lipophilic amine TBS Rapid absorption rate (due to activator A) High regenerability (due to regeneration promoter B) Excellent net CO 2 loading capacity (> 3 mol -CO2 /kg -sol ) Low energy requirement ( 2.5 MJ/kg -CO2 ) High chemical stability Novel concept: phase transition LLPS enhanced regeneration Regeneration at 80 C use of waste heat reduces CO 2 capture process costs 27

29 Acknowlegement CO 2 Capture Research Group: M.Sc. TU Dortmund University Dr. Frank Geuzebroek Ir. Mark Senden Dr. Xiaohui Zhang Shell Global Solutions Int. B.V. Technical Staff: Michael Schlüter Julian Gies Jerzy Konikowski Students: Robert Misch, Jing Chen Yu Qiao, Wanzhong Wang Onyekachi Nwani Frankfurt a.m

30 End Thank you for your attention Jiafei ZHANG Emil-Figge-Str. 66 (TCB) D Dortmund, Germany Tel.: (+49) TCB Campus of TU Dortmund